I use these inexpensive temperature and humidity sensors with my Home Assistant setup. They connect via Bluetooth to a Bluetooth dongle plugged into my Home Assistant server, allowing me to monitor conditions in different rooms without needing a separate hub. Each sensor runs on a single CR2032 battery, which lasts a couple of months depending on usage and signal strength.
The sensors also have a small built-in screen showing the current temperature and humidity, so the readings can be checked at a glance. They are designed to work with Tuya’s smart-home ecosystem and are remarkably affordable, costing less than €5 each. That makes them a practical choice for monitoring multiple rooms without spending much money.
The sensors that I use are generic Tuya bluetooth temperature en humidity sensor that look like the one in the image from this blogpost